Global Land Nitrogen Budget (N) – Model Intercomparison Project (MIP) is an international partnership aimed at Modeling, Accounting, and Predicting (MAP) the global land N/N2O budget and N–carbon (N-C) dynamics. This is achieved through Terrestrial Biosphere Model (TBM) intercomparison and TBM-data synthesis, under the umbrella of the Global Carbon Project (GCP) and the International Nitrogen Initiative (INI).
All participating TBMs simulate the full terrestrial nitrogen cycle and its coupling with the carbon cycle. As such, NMIP can be referred to as C-NMIP, as reflected in its logo.
NMIP supports major scientific assessments and initiatives, including the global N₂O budget (Tian et al. 2020; Tian et al. 2024), IPCC AR6 (Canadell et al. 2021), RECCAP2 (REgional Carbon Cycle Assessment and Processes), UNEP CCAC Nitrous Oxide Assessment (Thompson and Tian 2024), INMS (International Nitrogen Management Systems), Global Stocktakes, national assessments, and more.
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- In the first phase (NMIP1), the primary focus was on the global land N₂O budget, with the goal of understanding and quantifying the historical budgets of global and regional terrestrial N₂O fluxes, their environmental controls, and the uncertainties associated with model structure and parameters (Tian et al. 2018; Tian et al. 2019).
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- In the second phase (NMIP2), the focus remained on the N₂O budget (Tian et al. 2024). However, NMIP2 expanded its scope by demonstrating capabilities in quantifying other N species (e.g., NH₃, NO) and CO₂ fluxes (e.g., Gong et al. 2024), as well as supporting activities such as RECCAP2 regional GHG budget assessments in Africa (Ernst et al. 2024), East Asia (Wang et al. 2024), South Asia (Jain et al. (2025), North America (Poulter et al. 2025), MiddleEast and Central Asia (Qin et al. 2025) and multiple INMS activities.
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- In the third phase (NMIP3) and beyond, we will maintain our core focus on modeling the global land N budget, while expanding the scope to include N-C dynamics and future scenario projections. Additionally, we explore the broader nitrogen nexus – its interconnections with climate change, food security, water quality, and air quality – to better support the achievement of the United Nations Sustainable Development Goals (SDGs).
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Dr. Hanqin Tian, Director and Institute Professor, CES3 and GCP-Boston
on behalf of the NMIP Team
